Additional information to catch EA-75872

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -55,7 +55,7 @@ public class DefaultErrorMessages {
         DiagnosticFactoryToRendererMap getMap();
     }
 
-    private static final DiagnosticFactoryToRendererMap MAP = new DiagnosticFactoryToRendererMap();
+    private static final DiagnosticFactoryToRendererMap MAP = new DiagnosticFactoryToRendererMap("Default");
     private static final MappedExtensionProvider<Extension, List<DiagnosticFactoryToRendererMap>> RENDERER_MAPS = MappedExtensionProvider.create(
             Extension.EP_NAME,
             new Function1<List<? extends Extension>, List<DiagnosticFactoryToRendererMap>>() {
@@ -79,7 +79,8 @@ public class DefaultErrorMessages {
                 return renderer.render(diagnostic);
             }
         }
-        throw new IllegalArgumentException("Don't know how to render diagnostic of type " + diagnostic.getFactory().getName());
+        throw new IllegalArgumentException("Don't know how to render diagnostic of type " + diagnostic.getFactory().getName() +
+                                           " with the following renderer maps: " + RENDERER_MAPS.get());
     }
 
     @TestOnly

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DiagnosticFactoryToRendererMap.java

@@ -30,6 +30,20 @@ public final class DiagnosticFactoryToRendererMap {
     private final Map<DiagnosticFactory<?>, DiagnosticRenderer<?>> map = new HashMap<DiagnosticFactory<?>, DiagnosticRenderer<?>>();
     private boolean immutable = false;
 
+    // TO catch EA-75872
+    private final String name;
+    public DiagnosticFactoryToRendererMap(String name) {
+        this.name = name;
+    }
+    public DiagnosticFactoryToRendererMap() {
+        this("<unnamed>");
+    }
+    @Override
+    public String toString() {
+        return "DiagnosticFactory#" + name;
+    }
+    //
+
     private void checkMutability() {
         if (immutable) {
             throw new IllegalStateException("factory to renderer map is already immutable");